We have the equation for electric field E = kQ/
Where k is a constant, Q is the charge of source and d is the distance from center.
In this case E is inversely proportional to 
So, 
= 485 N/C
= 0.208 cm
= 0.620 cm
= ?

= 
= 53.20 N/C
Answer:
-15 m/s
Explanation:
The computation of the velocity of the 4.0 kg fragment is shown below:
For this question, we use the correlation of the momentum along with horizontal x axis
Given that
Weight of stationary shell = 6 kg
Other two fragments each = 1.0 kg
Angle = 60
Speed = 60 m/s
Based on the above information, the velocity = v is



= -15 m/s
What you really want to know is:
What is the net force ACTING ON the book ?
The answer is:
Before you ask how much net force there is, you should decide if there IS any net force.
-- If there's any net force acting on the object, then the object is accelerating.
-- If the object is not accelerating, then there is no net force acting on it.
-- The book is just laying there on the table. It is not accelerating. So there is definitely NO net force acting on it.
Answer:
The first object (black)
Explanation:
The thermal radiation of a body is governed by the Stefan Boltzmann Law, which is mathematically given as:

where:
(Stefan Boltzmann constant)
- Also the absorptivity and emissivity of a perfectly black body is maximum ( =1 ) therefore it absorbs all the heat energy incident on it and glows the brightest due to the perfect emission.
So here also the black object will glow brighter than the others.